The present invention pertains generally to digital/analog converters and in particular to a multiplexing arrangement for utilization therewith.
The proliferation of digital electronics has prompted a need for digital/analog converters for converting digital signals used therein to analog signals which are indigenous to the natural environment. Although there now exists a plethora of different types of such converters for converting a single digital signal to its analog equivalent, there is a noticeable lack of such equipment for efficiently converting a plurality of digital signals to a plurality of analog signals. For example, to convert a binary coded decimal (bcd) digital word, wherein each digit whose value lies in the range 0-9 is represented by a four-bit digital signal, to an analog equivalent, each digit would ordinarily be converted to its individual analog value through its own individual digital/analog converter, thus requiring as many converters as there are digits in the digital word. This replication of equipment is highly wasteful of resources, adding substantially to the cost of conversion.
When the digital signals constitute a varying bcd digital word indicative of dynamically varying information, quite often the analog signals corresponding to the individual digits thereof are used to visually display the converted decimal number. One venerable technique, based on analog signals developed long before digital electronics began burgeoning, employs a rotatable wheel for each digit that bears the numbers 0 through 9 around its rim and is driven by such as a synchro motor in response to the analog signal, with the automobile odometer being the most familiar example thereof. This technique is also commonly used in aircraft for displaying to the pilot various information such as bearings and distances used for navigational purposes. With this type of display, it is highly desirable to afford the viewer a dynamic indication of the displayed information as it varies so that changes can be anticipated which entails partially turning a wheel for a particular digit from one value to the next incremental value when the value of all the preceding digits is nine, thus indicating the approaching completion of a decadic count. As will be discussed hereinafter this obviates any information ambiguities. Although this feature, commonly referred to as geneva action, is intrinsic to information which is embodied in analog form, it is not so with respect to digital information.
With the foregoing in mind, it is primary object of the present invention to provide a new and improved digital/analog converter employing multiplexing for converting plural digital signals to plural analog signals.
It is a further object of the present invention to provide such a multiplexed digital/analog converter which affords a high degree of resolution albeit with a minimum amount of counting equipment.
It is still a further object of the present invention to provide such a multiplexed digital/analog converter which easily lends itself to affording geneva action.
The foregoing objects, as well as others, and the means by which they are achieved through the present invention may best be appreciated by referring to the Detailed Description of the Preferred Embodiment which follows hereinafter together with the appended drawings.